Need Help, Dead 460
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5th Wheeling
Joined: Dec 2019
Posts: 33
Likes: 2
Need Help, Dead 460
Howdy all, I need some advice on an engine problem. I was towing my RV with my '87 f250, 460/c6 and as I was coasting downhill the engine started backfiring. Before I could get my foot back on the throttle to give it some air, there was a massive backfire and then the engine died, no restart. Got it back to the house and started troubleshooting this morning, it's getting fuel, getting spark and all cylinders are building ~140 psi. I suspect some of the lifters may have collapsed, when I pulled the valve covers I was able to push down on quite a few of them and they felt sort of spongey. Pushrods look good, I checked the cylinders with an inspection camera and they look ok. If anybody has experience with this sort of problem, I'd love to gather some insight before I start throwing parts at it. Thanks in advance for your help!
-Sporty
-Sporty
Logistics Pro
Joined: Nov 2013
Posts: 3,928
Likes: 1,198
From: Mojave, Ca
Definitely sounds like a timing problem. Possibly a sheared roll pin on the distributor shaft as Sandymane mentioned. Could also be a failing Ignition module, but those usually start working again when it cools down.
Lead Driver
Joined: Oct 2016
Posts: 6,185
Likes: 633
From: Houston/Sugar Land
Im not sure about the pieces. Maybe Prototypemech can shed some light. Glad you found the root cause.
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5th Wheeling
Joined: Dec 2019
Posts: 33
Likes: 2
I pulled the dizzy, the roll pin sheared off clean as a whistle. Got the gear out and looked down into the opening but couldn't see the ends anywhere, hopefully they're back down in the sump. I had the imitial timing set at 15° btdc, havent touched the timing curve at all and it ran great right up until it didn't
Lead Driver
Joined: Oct 2016
Posts: 6,185
Likes: 633
From: Houston/Sugar Land
I pulled the dizzy, the roll pin sheared off clean as a whistle. Got the gear out and looked down into the opening but couldn't see the ends anywhere, hopefully they're back down in the sump. I had the imitial timing set at 15° btdc, havent touched the timing curve at all and it ran great right up until it didn't
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5th Wheeling
Joined: Dec 2019
Posts: 33
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I did, once I got it set and hooked the vacuum advance up it was showing ~30° btdc. I'll order a new dizzy and get it installed, in your opinion would it be worth replacing the lifters as initially suspected or no
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Lead Driver
Joined: Oct 2016
Posts: 6,185
Likes: 633
From: Houston/Sugar Land
This is what is supposed to do. When you pull the SPOUT the computer is removed from the timing program and 10 degree BASE TIMING is done manually by the user.. When you plug the SPOUT back in the computer is back in control of timing and adjust depending on preset parameters. I am not knowledgeable to know what to do about the lifters if anything.
Logistics Pro
Joined: Nov 2013
Posts: 3,928
Likes: 1,198
From: Mojave, Ca
The roll pin pieces are sitting in the bottom of the oil pan. Dont worry about them. You might be able to fish them out with a magnet at your next oil change. There is a mesh screen on your oil pick-up, so the pieces cant get into your oil pump.
I wouldnt bother replacing the lifters. Oil pressure keeps them pumped up. You'll hear your lifters tapping if they are bad.
I wouldnt bother replacing the lifters. Oil pressure keeps them pumped up. You'll hear your lifters tapping if they are bad.
Fleet Owner
Joined: Oct 2005
Posts: 20,786
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From: Kentucky
Thread Starter
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5th Wheeling
Joined: Dec 2019
Posts: 33
Likes: 2
rla2005 beat me to it, she's a carbureted monster. I'll just stick to the distributor for now and go from there if anything else is needed. I do know I'd be lost with this forum, I can't thank y'all enough for the help
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5th Wheeling
Joined: Dec 2019
Posts: 33
Likes: 2
Is there a good way to clear it if it is? I haven't noticed any pressure issues, I've got a standalone gauge and it shows 60-70 psi on startup and once it warms up it drops to 15-20 at idle and can get back up to around 40 when I'm getting into it. Not really sure if that's normal or not, this is my first bbf
FTE Legend
Joined: Nov 2015
Posts: 30,904
Likes: 4,122
From: Angier, NC
The pin goes thru the gear and shaft and out into the gear on the other side.
So the pin would be in 3 parts, each side of the gear & the shaft.
Now why did it shear is the real question?
Did a old valve seal make it by the pick up screen and jam the oil pump?
You may want to try and turn the oil pump to make sure it still turns.
When you use a socket on an extension use tape to hold the parts together so they dont fall down in to the motor.
Dave ----